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A brief description of a reciprocative device includes a basic door closer system which is controlled with liquid or gas. The device generally contains a piston assembly including a piston and sealing o-ring; piston rod varieties which include diametrically curved and non-curved surfaces; internal compression spring and hydraulic biasing operators; cylindrical piston body; sealed and non-sealed end caps; fluid restriction valves; attachment members; and the checking mechanism to which this invention pertains. Such door closer systems which comprise checking mechanisms are described in U.S. Pat. Nos. 2,732,920; 2,920,338; 3,032,806; 3,162,889; 3,566,435; 3,665,549; 4,777,698; and Canadian Pat. No. 623,038.
The checking mechanism is utilized to independently hold the door and door closer in an open or extended position for an indefinite period of time. The simplistic mechanism is axially mounted upon the extended rod of the device, for leveraging certain biasing forces controlled by the device into torsion. The torsion is urged between opposing points within an axial plane of the mechanism. The torsion causes substantial direct frictional pressure onto the surfaces of the piston rod. Thus. the mechanism frictionally checks the reciprocative function of the device with direct pressure causing the friction. Among the more elaborate checking mechanisms developed are illustrated in U.S. Pat. No. 4,194,264 to Soffregen (1980), and U.S. Pat. No. 4,815,163 to Simmons (1989). Through variously attached apparati comprising these mechanisms, an elaborate method is created to check the rod of the device similarly to the basic mechanism disclosed herein.
The prior art checking mechanism is usually metal stamped from a sheet material such as a predetermined sheet metal gauge. The mechanism comprises three main components: a) an aperture configuration bounded within a central structure; b) a trigger appendage; and c) a fixated joint connecting component a onto component b. The aperture configuration permits the mechanism to mount upon the rod of the device. The aperture configuration comprises opposing loci which define the opposing friction points. These points create the torsional pressure causing the friction within the axial plane. The central structure provides a boundary for the aperture configuration. The trigger appendage acts as a lever and provides a trigger point for abutment to the piston body. The central structure and the trigger appendage are typically flattened planes composed from the sheet metal gauge. The fixated joint angularly attaches the central structure onto the trigger appendage. The components differ slightly on the various prior art mechanisms, relative to the independent manufacturer's own design. However, the functionality of the three components are similar on most the prior art mechanisms.
The hold-open feature is manually activated by first opening the door to a desired position, thus extending the piston rod of the fixated door closer system from within the piston body. A counter-force is then normally created as a result of the system's biasing operators. The checking mechanism is axially mounted onto the rod through the aperture configuration, first by moving the mechanism to a desired position on the extended rod. Releasing the door, the biasing operators act to return the rod towards the normally retracted position within the body. The biasing force causes the mechanism to lever at the trigger appendage, once the body contacts the mechanism upon the trigger point.
The biasing force is redirected at the fixated joint which causes the checking mechanism to torsionally pivot on the center axis of the aperture configuration, and pivot on the axis of the piston rod. Thus, the mechanism pivotally engages onto the rod surface, urged upon the metallic edges of the opposing loci comprising the opposing friction points. The energy is substantially equalized and distributed to the points which interact and deliver the friction within the axial plane of the mechanism. The direct frictional pressure created by the points is applied onto the curved and non-curved surfaces of the piston rod, whereby the mechanism frictionally checks the device. More biasing force controlled by the device results in more torsional pressure causing the friction onto the surfaces of the rod. Sectionally dividing the mechanism through the common axis of symmetry and connecting the opposing points within the axial plane, connected to the trigger point, a simple angle is illustrated. Therefore, the reader can better understand the principles of pressure distribution, and the distance from the trigger point to the opposing loci comprising the opposing friction points.
Component a) the aperture configuration bounded by the central structure, comprises the opposing loci and points for urging the direct frictional pressure onto the surfaces of the rod. The loci are defined as the fulcrum locus and the counter locus, separated by the center axis. Both loci are composed upon the common axis of symmetry. In the prior art, each locus comprises a single opposing friction point which torsionally delivers the substantial direct frictional pressure onto the surfaces of the rod. In prior art, the opposing friction points are composed upon the common axis of symmetry. Thus, the direct frictional pressure is also substantially aligned upon the common axis of symmetry. The friction points are described as any area which substantially provides contact upon the surfaces of the rod. The uniqueness of the aperture is often specifically limited to the rod applied thereto, and will not permit the mechanism to interchange with other devices comprising various other types of rod diameters.
As a result of the two opposing friction points being located upon the common axis of symmetry, the distance between the opposing points is dictated by the diameter of rod along the common axis of symmetry. In prior art designs, placement of two opposing friction points at any other location other than upon the common axis of symmetry would be impossible and would render the simplistic mechanism inoperable. Therefore, the distance between the points is limited to not any lesser a distance than the diameter of the rod, and can not be modified. The geometry of prior art aperture configurations define the most major limitations for the art.
First, because the distance between the loci is defined by the greatest diametric sectional distance of the piston rod along the common axis of symmetry, the two opposing points are extremely located apart from each other and therefore minimally centralized upon the common axis of symmetry. Only a modification of the piston rod could effect a prior art checking mechanism to possibly check away from the common axis of symmetry. Canadian Pat. 623,038 to Mallory (1960) shows various mechanisms designed for usage upon modified piston rods comprising curved and non-curved surfaces. However, as described in the patent this notion was created solely to prevent any rotation of checking mechanism upon the piston rod surface, rather than provide any uniqueness for the two opposing friction points (number 22). The points again remain aligned upon the common axis of symmetry, and provide no lesser a distance between the points than the diameter of the rod.
Secondly, the two opposing friction points interact to provide only a singular source of substantial direct frictional pressure, linearly aligned upon the common axis of symmetry. Thus, there is no substantial lateral direct frictional pressure provided by the points away from the common axis of symmetry. If lateral pressure were available, such pressure could provide stabilization and securement onto the surfaces of the rod. For balance, the two points applying the direct frictional pressure must always remain linearly aligned and dependent upon the common axis of symmetry. It shall be noted that various prior art checking mechanisms including those equipped with a more narrow trigger appendage, may demonstrate a slight lateral rotation due to the lack of balance for the two opposing points. However, because the rotation of the checking mechanism is not maximized, a close examination of such mechanisms reveals that no substantial lateral direct pressure occurs.
Some checking mechanisms have an aperture configuration which is circular shaped, slightly larger than the diameter of the piston rod. When the circle is tilted as the mechanism engages the rod, the circular configuration conforms to an elliptical shape. The results again provide that only two substantial opposing friction points within the axial plane, check the surfaces of the rod. U.S. Pat. No. 2,920,338 to Falk (1960) (FIG. 3) also shows a circular configuration. The two loci comprise minimal points, however as the two loci wear out they tend to flatten and create slightly larger friction points as will be further discussed below.
Certain less comnmon types of door closer systems comprise piston rods having non-curved surfaces. The checking mechanisms for these devices comprise loci with substantially larger contacting areas. However, these designs are limited to the non-curved surfaces of the squared piston rod varieties. Thus, the two opposing friction points are dictated by the diametric sectional distance of the piston rod upon the common axis of symmetry. U.S. Pat. No. 3,032,806 to Mallory (1962), (FIG. 5) specifically shows checking mechanisms comprising such designs with substantially larger loci (number 26).
A separately related yet disadvantageous factor apart from the inferior checking mechanism design, is that modern piston rods providing curved and non-curved surfaces are often very smooth. The surfaces actually becomes polished and smoother with frequent usage. This smooth surface lacks any contributing traction for the two opposing friction points. A slight film of oil may also contribute to the lack of traction. During testing conducted involving prior art, worn door closer systems comprising smoothly polished rods were retrofit with brand new checking mechanisms. Results indicated that slippage soon occurred on the smooth rods, even when mounted with the brand new mechanisms.
Component b) the trigger appendage acts as a lever to leverage the mechanism for pivotal engagement upon the device. The trigger appendage transposes the biasing forces controlled by the device into the direct frictional pressure upon the rod. The trigger appendage provides a trigger point for abutment onto the piston body. The trigger point varies upon the surface of the trigger appendage. The trigger point is defined upon a trigger plane. The trigger plane generally projects from the origin axis for the fixated joint, projected to the trigger point abutting the body of the device. Because the surface of the trigger appendage is substantially flat and also projects from the origin axis, the trigger plane therefore remains fixated as the trigger point varies upon the surface of the trigger appendage. Thus, in prior art the trigger point is best defined upon a non-variable trigger plane. The flat surface of the trigger appendage offers no other adjustable features for the varying trigger point.
Prior art checking mechanism provide a substantially similar distance between the three functional points of leverage. Specifically, the distance from the trigger point to the fulcrum locus is not much greater than the distance between the opposing friction points within the loci. An average door closer system comprising a 1.25" (32 mm) piston body and 0.313" (8 mm) piston rod, comprises a 1.5-to-1 average leverage ratio for the mechanism. Again, unless the piston rod is modified the distance between the two opposing points can not be modified. Resultantly, the sectional distance between the two opposing points may never become altered or decreased to partake in any possible leverage advantage for the trigger point.
It may seem obvious that to obtain an increase in leverage ratio, the length of the trigger appendage should therefore be increased. However, merely increasing the length of the fixated trigger appendage would require decreasing the fixated joint, because of the flattened nature comprising the trigger appendage. The flattened surface of the trigger appendage limits the trigger point to the non-variable trigger plane, and will not compensate for an increase in the surface area resulting from any lengthening of the trigger appendage. Lengthening the trigger appendage would also place more stress onto the joint, further weakening the mechanism which often does not comprise hardness or temper modification for the soft sheet steel gauge.
The trigger appendage must create a functional gap between the central structure and the piston body. The gap must prevent any simultaneous touching of the central structure against the body, which disrupts the direct frictional pressure created by the opposing points upon the rod. The flattened trigger appendage also offers less surface area to increase the functional gap. As the checking mechanism wears and fatigues, the trigger point changes and climbs the surface of the flattened trigger appendage. Due to the non-variable trigger plane, the functional gap is reduced at the same rate as the climbing trigger point. Thus, there is less surface for the trigger appendage to provide certain variable extension and adjustment for a wearing checking mechanism. The flattened trigger appendage also offers less universalness to adapt a single checking mechanism to various devices.
Component c) the fixated joint comprises an angular connection between the central structure and the trigger appendage. The joint angularly directs the biasing forces controlled by the door closer biasing operators, to the opposing points torquing within the axial plane which cause the direct frictional pressure. All prior art checking mechanisms disclosed demonstrate a fixated joint which is greater than 90 degrees at the origin for both components. Some modern checking mechanisms comprise angular fixated joints as great as 120 degrees at the origin. The angle at the origin is determined by projecting an axis (face axis) upon the face of the central structure, and projecting the other axis (origin axis) from the origin for the trigger appendage. The origin may be determined as the best angle created between both components.
Among other factors, the angle must limit the central structure from simultaneously touching against the piston body along with the trigger point. Any simultaneous touching of the central structure disrupts the torsional engagement between the opposing friction points urged upon the rod. Therefore, the degree of the angle for the fixated joint must contribute to the functional gap between the central structure and the piston body. Because the prior art mechanisms are primarily manufactured from common sheet steel which is relatively soft, the joint is therefore subject to fatiguing which reduces the functional gap. In order to provide a mechanism which does not slip, the joint should be both fixated and capable of withstanding sufficient pressure. U.S. Pat. No. 3,566,435 to Nakamura (1971) shows a perpendicular angular joint which is not fixated. Resultantly, this mechanism provides an intentional slipping feature as described within the contents of the patent.
Another known problem contributing to a substantial reduction in the functional gap is defined by the natural wearing of the metallic edges which comprise the opposing friction points. The wearing causes the points to flatten which may result in a loss of substantial direct frictional pressure. Thus, the pressure becomes distributed over the two flattened points instead of being forcefully urged, as upon sharper biting edges comprising the loci of a brand new checking mechanism. A decrease in the functional gap may also be caused by the lateral rotation of the mechanism as previously described. Conclusively, any substantial reduction in the functional gap may ultimately render the mechanism useless.